Burner tuyere arrangement for a blast furnace



Jan. 19, 1965 J. w. CARLSON 3,166,621

BURNER TUYERE ARRANGEMENT FORABLAST FURNACE Filed March 16. 1961 R% WOHM E T 0 TN .m f n o W IMW 00 United States Patent 3,166,621 BURNERTUYERE ARRANGEMENT FOR A BLAST FURNACE John W. Carlson, Pueblo, Colo.,assignor' to The Coloratio Fuel and Iron Corporation, Denver, Colo., acorporation of Colorado Filed Mar. 16, 1961, Ser. No. 96,171 2 Claims.(Cl. 26641) This invention relates to blast furnace operations, and hasfor its object the provision of an improved combustion process forheating the. charge and effecting the reduction of the iron ore. Theinvention aims to eliminate at least a substantial, portion of the cokecustomarily used and to efiect the heating and conversion reactions withhydrocarbon. liquids and natural gas.

For many years suggestions have been made in the literature to usenatural gas, other hydrocarbon gases and various petroleum products inthe blast furnace either as a substitute for, or as a supplement to, theuse of coke. The available hydrocarbon gases such as natural gas(methane) are so high in hydrogen that they lack the requisite thermalcapacity and the water formed as a product of the reactionsisobjectionable.

The petroleum liquids such as crude petroleum or distillation residuessuch as bunker-C are difiicult to handle in burners or tuyeres becausethey decompose in the burners and plug the orifices with carbondeposits.

As a result of considerable. experimentation with the use of thesefluids I discovered a simple and practical process for burning aneffective mixture of a heavy high carbon material such as bunker-Cdistillation residue and methane gas. In accordance with the process ofmy invention I bring together in a single nozzle the liquid hydrocarbonand natural gas and charge them as a mixture into acombustion-supporting air stream and direct the resultinghigh-temperature flame through the tuyeres of the blast furnace. In apreferred and advantageous adaptation of my process I discharge theliquid petroleum fuel into a surrounding stream of natural gas andaccomplish not only dispersion of the liquid in the gas, but form anenvelope of gas surrounding the pipe carrying the liquid which preventsover-heating of the liquid in the pipe and the deposition of carbon. Iprefer to .carry the liquid through a relatively small pipe mountedwithin a larger gas pipe and to have their discharge openings at aboutthe same place so that these fluids, released under pressure, becomeintermixed preferably just in advance of the point of combustion and aredirected into the axis of the air stream.

This dispersion of the heavy oil in the gas results in a better mixingwith the air and better combustion. The most important benefit is in thesupply to a blast furnace of an effective blend of a liquid fuel havinga high ratio of carbon to hydrogen and hence high heat capacity with themethane gas of lower heat capacity.

The invention provides a practical means of utilizing in a blast furnacea mixture of the cheap and burdensome bunker-C oil and the cheap naturalgas as a substitute for the much more costly coke now widely used.

The invention provides also an improved burner including a nozzle forintermixing liquid and gaseous fuel, burning the mixture and directingthe combustion products of the mixture into a blast furnace preferablythrough a tuyere. The burner includes means for charging the liquid andgas mixture into an air duct of a blast furnace tuyere. One feature ofthe improved burner is in the cooling of the nozzle through which theliquid fuel and gas are discharged to prevent carbon deposits. Thenozzle preferably comprises a small tube for liquid fuel inside andsurrounded by a much larger duct or pipe for gaseous fuel. Thesurrounding envelope of gas shields the small tube and preventsoverheating and cracking of the liquid fuel with deposition of carbon.Another feature of the burner is the attachment of a bimetallicheatresponsive element to the burner and its connection to a signaldevice to, signal overheating of the burner.

These and other features of the invention will be better understoodafter considering the following discussion and accompanying drawings, inwhich I FIG. 1 is a side view, partly in section, of a burner of theinvention installed in a blast furnace, and

FIG. 2 is a fragmentary enlargement of the burner of FIG. 1. I

The complete burner 1 of the invention illustrated in the drawings ismounted in the water cooled tuyere opening 2 in the wall 3 of a blastfurnace. It is to be understood that each tuyere opening will have asimilar burner. As illustrated, the burner is an adaptation of the usualtuyere system for blowing air into the blast furnace consisting of atuyere 4 which has an annular space 5 for cooling water forced inthrough pipe '6 and out through pipe 7. The air duct 8, known as a blowpipe, is connected by the flanges 9 to the air supply pipe 10 whichleads to the usual bustle pipetnot shown). The sighting device 11 ismounted in the pipe 10.

The fuel nozzle 15 comprises an outer pipe 16 for gas and a concentricsmaller inner pipe 17 for liquid fuel. This nozzle is water cooled,advantageously by" mounting it in the water cooled tuyere 4 as shown.This may be done by welding, or by casting a copper tuyere 4 around aMonel metal or other alloy or copper pipe 16.

The nozzle pipe 16 is connected to the natural gas supply pipes 18 and19. The pipe 18 has an attached packing gland 20 through which theliquid fuel supply pipe 21 passes and is either connected to, or iscontinuous with, the pipe 17. In an effective burner construction, thepipes 18 and 19 are preferably about in diameter and pipe 16 may be thesame size or a little smaller. These pipes may be of steel or copper.The pipes 17 and 21 may be A" copper tubing. The gland 20 may be a pipeunion having the copper tube 21 welded to the union half, as shown, toform a tight connection. It will be noted that the end of the nozzle 15is so constructed that it projects into the space Within the tuyere 4and in the air stream in such a manner that the mixture is directed intothe center of the air stream. The pipe 17 preferably ends short of theend of pipe 16.

The aforementioned nozzle is effective for carrying out a preferredprocess of the invention. However, I may change the construction of theburner by eliminating the small tubes 17 and 21. With this burner I mayintroduce the liquid fuel through the pipe 19 and the gas fuel throughthe pipe 18 or I may reverse the order and introduce the liquid fuelthrough pipe 18 and the gas fuel through pipe 19, but in each case Ieffect intermixing of the fuels at place 24.

The bimetallic element 22 is preferably in the form of a band attachedto the air pipe 8 and the electric wires 23 lead to a suitabletemperature recording or signal device (not shown).

In carrying out a blast furnace combustion process of the invention withthe burner illustrated, I prefer to use bunker-C distillation residuebecause of its high carbon content and low cost. However, I may useother liquid hydrocarbon fuels. When using bunker-C fuel it should beheated to decrease its viscosity and facilitate its flow and dispersioninto the natural gas when it issues from pipe 17. I prefer to heat thisliquid to a temperature of from 120 F. to 250 F. and to discharge it ata pressure varying from 30 to psi. The preferred ratio of bunker-C fuelto natural gas is from 0.5 to 4 pounds of bunker-C fuel per pound ofnatural gas.

The methane or natural gas is passed through pipes 19, 18 and 16 as anenvelope surrounding pipe 17. This gas is preferably used at normaltemperatures and under a preferred pressure of from 30 to 100 p.s.i. Theliquid and gas impinge upon each other at the end of nozzle and thisresults in an effective dispersion and intermixing with the air intuyere 4. The liquid oil is accordingly atomized and this results ineifective combustion. This heavy oil can be supplied to the burner overlong periods without plugging the nozzle 15 because the surroundinglayer of cooler natural gas in pipe 16 serves as a thermal barrier andprevents the heating of pipe 17 to a point where the oil is cracked withresulting carbon deposits which can plug the nozzle.

Changes in the furnace operation, which occur frequently, are noticed byvisually observing the iron and slag and by analysis of furnace gas. Ifcorrection be necessary, it can be started immediately by varying theflow of gas and liquid fuels through the nozzle and into the air streamand into the furnace hearth in but a few seconds or less. Not only canthe amounts and proportions of gas and liquid fuel be varied, but alsowith respect to the other three control measures. Moreover, these cantake effect immediately instead of the usual ten to sixteen hoursrequired to change a coke charge and have it arrive in the hearth.

The gas and liquid fuel mixture can be used to replace all or a part ofthe coke presently used, and can be used in connection with chargesincluding briquets of iron oxide fines and carbon or coke, or when coalchar or other forms of solid carbon fuel are used.

I claim:

1. A burner for a blast furnace comprising a tuyere formed as a unitarymember having an inner air passage and a cooling jacket for coolingwater, means for circulating cooling water in and through said coolingjacket, said cooling jacket having an inner wall defining the airpassage and a rearward wall which closes the cooling jacket for coolingwater, and a nozzle for burning liquid fuel comprising a pipe for thedischarge of a cooling gas passing through the rearward wall and theinner wall of the cooling jacket and extending into the air passage, anda tube mounted inside the pipe for charging liquid fuel into the innerair passage.

2. A burner as defined in claim 1 in which the tuyere is formed as aunitary casting and the metal of the tuyere is cast over the pipeforming tight joints therewith.

References Cited by the Examiner UNITED STATES PATENTS 325,293 9/85Weber 42 370,251 9/87 Field 26641 X 502,482 8/93 Dauber 26629 XR 966,7048/06 Pickles 266-41 1,393,749 10/21 Carstens 266-41 1,718,732 6/29Danforth 7-543 1,873,996 8/32 Cunningham 266-41 1,962,593 6/34 Henry266--41 2,446,511 8/48 Kerry et al. 26641 2,582,615 1/52 Wolfe et al.266-41 XR FOREIGN PATENTS 679,755 8/39 Germany.

MORRIS O. WOLK, Primary Examiner.

MARCUS U. LYONS, DAVID L. RECK, JAMES H.

TAYMAN, JR., Examiners.

1. A BURNER FOR A BLAST FURNACE COMPRISING A TUYERE FORMED AS A UNITARYMEMBER HAVING AN INNER AIR PASSAGE AND A COOLING JACKET FOR COOLINGWATER, MEANS FOR CIRCULATING COOLING WATER IN AND THROUGH SAID COOLINGJACKET, SAID COOLING JACKET HAVING AN INNER WALL DEFINING THE AIRPASSAGE AND A REARWIND WALL WHICH CLOSES THE COOLING JACKET FOR COOLINGWATER, AND A NOZZLE FOR BURNING LIQUID FUEL COMPRISING A PIPE FOR THEDISCHARGE OF A COOLING GAS PASSING THROUGH THE REARWARD WALL AND THEINNER WALL OF THE COOLING JACKET AND EXTENDING INTO THE AIR PASSAGE, ANDA TUBE MOUNTED INSIDE THE PIPE FOR CHARGING LIQUID FUEL INTO THE INNERAIR PASSAGE.